The invention relates to an improved tree guard for protecting the tender, immature bark of young trees, in general, young fruit trees, decorative trees and shrubbery, and a lock adapted to be used in such a tree guard.
The bark of young trees includes a vital but fragile vascular layer that is crucial to the survival of the tree. Water and nutrients move from the roots to the tips of the highest branches through the vascular layer. If however, the vascular layer is damaged by an injury to the bark, the nutrients are cut off from certain parts of the tree.
In time, the vascular tissue comes to be protected by a thick cork layer commonly known as bark. The thicker the bark becomes the better it protects the vascular layer. Early in a tree's life, however, the young, thin bark is insufficient to prevent mechanical damage to the vascular layer and ensuing loss of tree vitality. Moreover, some fruit trees and other commercially valuable trees continue to be vulnerable to such damage throughout a large portion of their life span. It has therefore been recognized for some time that it is desirable to protect the fragile bark and its underlying vascular layer through the use of a tree or plant guard fully or partially encircling the tree.
A number of different types of styles and shapes of tree guards have been devised. These range from thin, flexible, coiled guards, which are intended to prevent rodent damage only, to elaborately designed guards designed to protect the tree's roots and base while limiting competition for the tree's resources. It is also known to use short lengths of plastic corrugated weeping tile with a split formed down one side to protect the base of the trees. However, plastic tile is relatively stiff, difficult to work with and sometimes tends to slice into the tree during installation due to the sharp edges of the required split.
U.S. Pat. No. 2,782,561 issued to Smith teaches a plastic guard that is both a bedding edge for the tree and ostensibly a tree guard. U.S. Pat. No. 5,048,229 issued to Campbell, teaches a rigid tree guard made of perforated plastic pipe. U.S. Pat. No. 4,642,938, issued to Georges et al., teaches a rigid conical tree guard and anti-frost device which is fastened together at a fastening flange running up the outside of the guard. Paper and burlap wrapping materials are also known but will not stand up to repeated mechanical damage.
The known tree guards that prevent some forms of mechanical damage require either a relatively complex structure or additional fastening components adapted to hold the guard in place around the tree. It has not hitherto been possible to simply and inexpensively protect young or fragile trees and saplings from impact injuries with a tree guard of simple installation and manufacture.
In addition, it is desirable in some circumstances that lawn maintenance equipment such as lawn mowers and line trimmers be used to trim grass or weeds immediately adjacent to a tree without damaging the tree itself. Such lawn equipment can cause serious impact damage to unprotected bark either through forceful low velocity impact by the body of the device on the tree or through high velocity impact by a rotating cutting line or blade, or by a projectile thrown thereby against the tree. In order to protect trees from such damage, it is necessary to ensure not only that the lawn equipment is prevented from impacting the tree but also that the guard itself will cause as little damage as possible to the tree should it be propelled against the tree. Accordingly, substantially rigid tree guards are not desirable for use where such equipment must be brought very close to a tree. It has not hitherto been possible to provide a tree guard that will permit use of such equipment immediately adjacent to a tree while significantly reducing the chance of undesirable impact damage to the tree.
It is an object of this invention to provide a tree guard that is simple to use and inexpensive to manufacture, and which offers protective capabilities superior to those offered by the prior art. It is also an object of the present invention to provide a process for the manufacture of such tree guards in an economical and inexpensive manner. It is also an object of this invention to provide a locking mechanism adopted to be used in a tree guard of the type described herein.
According to one broad aspect of the invention, there is provided a tree guard having a generally rectangular, single sheet of flexible plastic, a first elongate locking strip and a second elongate locking strip. The flexible plastic sheet has a first face, a second face, a first end and a second end. The sheet is bendable so as to form a cylinder with the first end adjacent to the second end. The first locking strip is attached to and runs along the first end of the sheet. The first locking strip includes a bottom wall, an inner side wall and an outer side wall which define a groove. A retaining bead runs along one of the side walls. The second locking strip includes a locking flange, which is generally complementary in shape to the groove in the first locking strip, and retaining means for engaging the retaining bead of the first locking strip when the second locking strip is inserted into the groove. The second locking strip is attached to the second end of the sheet and arranged generally parallel to the first locking strip.
According to another broad aspect of the invention, there is provided a locking strip having an elongate base portion and an elongate, flexible, L-shaped flange attached thereto. The base portion includes an inner side wall. The L-shaped flange includes a bottom wall and an outer side wall. The bottom wall runs along the inner side wall and projects generally perpendicularly therefrom a first distance. The outer side wall runs along the bottom wall and projects generally perpendicularly a second distance so that the inner side wall, the bottom wall and the outer side wall define a U-shaped groove. The outer side wall has a thickness no greater than the first distance. A retaining bead runs along the outer side wall and is spaced from the bottom wall a third distance, the third distance being greater than one-half of the second distance.